The present invention relates generally to security systems and particularly to motion detectors for security systems, such as passive infrared (IR) detectors.
Motion detectors for security systems are well known. The most common type of motion detector is a passive IR detector that detects motion from animate, moving objects that that emit IR, such as humans and animals. (The term xe2x80x9cobjectsxe2x80x9d as used herein includes animals and humans.)
Animals, and especially cats, pose special problems for environments employing security systems with motion detectors because they are usually free to roam spaces in which motion detectors are employed (xe2x80x9cprotected spacexe2x80x9d) and hence, when the security system has been armed, they can set off an alarm when they enter the protected space. Although the protected spaces are usually zoned and specific zones can usually be bypassed, this defeats the purpose of installing the motion detector in the protected space in the first instance.
Humans also pose a problem because they might forget that the protected space has been armed with a motion detector and wonder into it. Again, though protected spaces can usually be bypassed, bypassing defeats the purpose of the alarm system, and also humans can forget to bypass the protected zones when they arm the system.
It is desirable to provide a means by which protected spaces can remain armed and protected by motion detectors, but which allows authorized objects to roam within those spaces without setting off the alarm. The present invention achieves this goal.
An object that can be sensed by a motion detector is equipped with a small, battery powered transponder. A motion detector has (either internally or externally) a transceiver adapted to provide a query signal. If the object is within range of the query signal, the transponder responds with a transponder signal. The transceiver is responsive to receipt of the transponder signal to prevent the detection of motion from causing an alarm.